1. Field of the Invention
The subject invention relates to an electrical socket for a gull wing semiconductor package.
2. Description of the Prior Art
Semiconductor packages are arranged with several lead configurations denoting their use. One such semiconductor package is known as the gull wing package and includes a plurality of leads extending from the package body from all four side edges of the package body and all leads extending outwardly from a common flat plane. The leads are then bent downwardly and then flattened to form a plurality of feet which are in a plane which is beneath the bottom surface of the package body.
Typically, all semiconductor packages are tested in some manner to ensure their proper functioning, including burn-in testing where the devices are inserted into sockets and installed within large convection ovens and the packages are operated at elevated temperatures.
Semiconductor packages are now being manufactured in the four sided gull wing configuration with the lateral centerline between adjacent leads spaced apart 0.025 inches with as many as 244 leads extending from the package body. With an insertion force on each lead being approximately 0.25 pounds, the total insertion force for such a semiconductor package would be as high as 61 pounds total. The problem which resultantly exists is the necessity of an insertion and latching means which can progressively install the package leads yet maintain and retain the semiconductor package in an electrically connected condition with the terminals of the burn-in socket.
The package known as the gull wing semiconductor is a very fragile component and, often times the package is installed within a carrier which includes an insulative housing to surround the package body. The carrier is placed within the socket during the burn-in testing and, when completed, the carrier and package are removed and the semiconductor package is shipped within the carrier for protection of the package leads. One style of burn-in sockets presently available requires the semiconductor package and the carrier to be inserted within the sockets and requires the installer to exert a force directed onto the package carrier to a position where the package carrier clears a latching mechanism. Three problems are presented by such an arrangement.
First, burn-in cycling requires a massive "burn-in board" which is a printed circuit board having densely packed burn-in sockets aligned side-by-side and end-to-end on the board. To require the installer to insert this small semiconductor and carrier within the sockets requires a great deal of dexterity, as the carriers are in the range of one inch square, and also requires a lot of physical strength given that the force of 60 pounds must be concentrated on that small of a carrier.
Second, the contacts within the sockets can easily be damaged by the installer, if the carrier is over extended within the socket housing, the contacts can be overstressed to the point of plastic deformation.
Third, these connectors are very labor intensive to use as the packages and carriers usually have to be hand installed and removed, with the covers manually closed opened, respectively.
Another style of burn-in connector is shown in U.S. Pat. Nos. 4,623,208 and 4,715,823; which include covers which overlie the plurality of electrical terminals within the housing. The terminals include portions in engagement with the cover, such that, downward movement of the cover rotates the contacts within the housing. One disadvantage to these type of connectors is that as the number of contacts increases, the downward force on the cover member too increases, to a point where the cover is very stiff and rigid, and not easily moved. This is predominantly true due to the geometry of the combination of the cover and the electrical terminals; in that the cover pushes directly against the terminals in a vertical direction downwards. The torque which can be obtained from this arrangement is limited however, since the terminals are not very wide, the moment arm is typically short, resulting in a small torque.